Kernel: Fixed dangling icons and background color in TreeTableViewers

fixes issue 4147

Issue-Url: af3#4147 (closed)

changed milestone to %AF3 2.20 - Feature Freeze

added State::New label

requested review from @bergemann

assigned to @barner

mentioned in issue af3#4147 (closed)

When reviewing and testing, make sure to also check the background color as descirbed in the comment in af3#4147 (closed)

added 1 commit

• 52d23872 - GREEN

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approved this merge request

enabled an automatic merge when the pipeline for 52d23872 succeeds

mentioned in commit db31ed5b

merged